$OpenBSD: patch-setupext_py,v 1.15 2014/12/23 13:48:54 daniel Exp $
--- setupext.py.orig	Wed Oct 22 21:54:01 2014
+++ setupext.py	Tue Dec 16 11:30:47 2014
@@ -1365,6 +1365,7 @@ class BackendTkAgg(OptionalBackendPackage):
             ]
 
         ext = make_extension('matplotlib.backends._tkagg', sources)
+        ext.include_dirs.extend(['${X11BASE}/include'])
         self.add_flags(ext)
         Numpy().add_flags(ext)
         LibAgg().add_flags(ext)
